In the modern society, the science, the technology and the civilization are getting more progressive day by day. Lot types of electronic devices like smart phones, personal computers, desktop PCs, notebook PCs, servers, and air conditioners are highly related with people's daily life. The electronic devices usually generate heats during operating, so that the electronic devices may crash or breakdown when operating under high temperature environment. Under this circumstance, the fans are applied to the electronic devices for heat-dissipation. By enhancing the circulation, the heats generated by the electronic devices are effectively reduced, and the life of the electronic devices is extended and the stability of the electronic devices is enhanced.
Generally, the conventional fans are driven by motors so as to rotate and generate airflows. The output-pressure outputted by the fans is substantially in direct proportion to the radius, i.e. the pressure is increasing from the position representing smaller radius to the position representing larger radius. Therefore, the output-pressure is largest at the outer position of a blade of an impeller and smallest at the central area of the blade of the impeller. The difference of the output-pressures causes an uneven problem during doing work of the blade of the fan. To solve this uneven problem, a bigger or a larger fan is conventionally used to generate airflows with enough output-pressure so as to satisfy the practical demands.
However, the lifestyle and the trend of technology nowadays are significantly changed, and the requirement of the electronic devices is also changed. For designing or manufacturing a product with smaller size and thinner thickness, the factors of limitations of space and location must be considered. It is the reason why the larger fan and the larger motor are not used when considering the higher efficiency or larger area of heat-dissipation. As a result, the uneven problem during doing work still remains. Not only the requirement of higher efficiency and larger area of heat-dissipation cannot be satisfied, but also the expected performance cannot be implemented, which causes the waste of space and energy.
There is a need of providing an improved fan and a pressure-increasing blade assembly thereof to obviate the drawbacks encountered from the prior art.